Hmm, it’s quite some time since I tried this path but I don’t recall any problems with the post-grove party triggering.

Has the quest for attacking the grove correctly updated in the journal and say everything has completed? Just wondering if someone’s still alive somewhere. IIRC after killing the druids you go back to Minthara who may be in the cave where Zevlor camped out. Did that happen? She didn’t die during the assault did she?

"You may call it 'nonsense' if you like, but I've heard nonsense, compared with which that would be as sensible as a dictionary!"